Full rewrite under bash >= 5.1

[F-Hauri]

I've completely rewrite this

• Running backgrounded bc to avoid multiples forks
• Reducing a lot, whole execution time, by running all test at same time, parallelized,
• ping local DNS before adding them to dns list
• compute averages by domain
• test command line arguments by case instead of multiple if..then
• use of bash arrays instead of string-with-spaces for arrays
• use of bash integer whenever possible
• used function instead of variable for drill vs dig
• created a function hasipv6 and move them to be used only if needed.
• Added very useful spinner

Not anymore on Github, you may find my work at
https://f-hauri.ch/vrac/dnstest.sh

( Then consider https://sfconservancy.org/GiveUpGitHub/ ;)

[F-Hauri]

Correction:

• Add +2 at sort -nk command

[eabase]

very interesting